Tapestry 5.3.1 is a bug fix release and represents a drop-in replacement for the previous stable 5.3 release.
Full details are in the release notes, but here's a few highlights:

@PerThread scope honored when service is created using autobuild

@ActivationRequestParameter encoded to be URL friendly

Exceptions while compressing JavaScript are fully reported

All forms/submission working normally after FileUploadException is raised

Asset path prefix configurable

As usual for each Tapestry5 release we've made great efforts to ensure an easy upgrade path; but be sure to read the upgrade notes carefully as some interfaces and methods that were deprecated in Tapestry 5.0 or 5.1 have been removed: you should recompile and retest your application after upgrading your dependency. If you still have problems, use the Tapestry user mailing list to get support.